• 대한기계학회논문집
• /
• 제15권1호
• /
• pp.229-240
• /
• 1991

본 연구에서 사용한 이론과 제시된 방법의 타당성을 검토하기 위하여 익열 간 극이 무한대인 단일 익형 주위의 유동장을, 최근에 개발된 계산방법인 Lambda방법을 사용한 Dadone의 해석결과와 비교하였고, 범용의 압축기 익형인 NACA65게열 익열 유동 에 대한 Herrig의 실험값, 그리고 미분해석에 의한 점성-비점성 상호작용 방법을 사용 한 Hansen의 계산값고, 이들 조건과 동일한 상태에서 본 연구에서 제시한 방법으로 계 산한 결과와 만족할 만한 일치를 얻었다.

• Journal of Biosystems Engineering
• /
• 제36권2호
• /
• pp.96-108
• /
• 2011

Several methods of in-field measurements of Nitrogen and other soil properties using cores extracted by a hydraulic soil sampler were evaluated. A prototype core scanner was built to accommodate Veris Technologies commercial Vis-NIRS equipment. The testing result for pH, P and Mg were close to RPD (Ratio of Prediction to Deviation = Standard deviation/RMSE) of 2, however the scanner could not achieve the goal of RPD of 2 on some other properties, especially on nitrate nitrogen ($NO_3$) and potassium (K). In situ NIRS/EC probe showed similar results to the core scanner; pH, P and Mg were close to RPD of 2, while $NO_3$ and K were RPD of 1.5 and 1.2, respectively. Correlations between estimations using the probe and the core scanner were strong, with $r^2$ > 0.7 for P, Mg, Total N, Total C and CEC. Preliminary results for mid-IR spectroscopy showed an $r^2$ of 0.068 and an RMSE for nitrate (N) of 18 ppm, even after the removal of calcareous samples and possible N outlier. After removal of calcareous samples on a larger sample set, results improved considerably with an $r^2$ of 0.64 and RMSE of 6 ppm. However, this was only possible after carbonate samples were detected and eliminated, which would not be feasible under in-field measurements. Testing of $NO_3$ and K ion-selective electrodes (ISEs) revealed promising results, with acceptable errors measuring soil solutions containing nitrate and potassium levels that are typical of production agriculture fields.

• Journal of Biosystems Engineering
• /
• 제33권1호
• /
• pp.30-37
• /
• 2008

Dynamic excitation and response analysis is an acceptable method to determine some of physical properties of agricultural product for quality evaluation. There is a difference in the internal viscoelasticity between sound and defective fruits due to the difference of geometric structures, thereby showing different vibration characteristics. This study was carried out to develop a portable piezoelectric film-based glove sensor system that can separate internally damaged watermelons from sound ones using an acoustic impulse response technique. Two piezoelectric sensors based on polyvinylidene fluoride (PVDF) films to measure an impact force and vibration response were separately mounted on each glove. Various signal parameters including number of peaks, energy ratio, standard deviation of peak to peak distance, zero-crossing rate, and integral value of peaks were examined to develop a regression-estimated model. When using SMLR (Stepwise Multiple Linear Regression) analysis in SAS, three parameters, i.e., zeros value, number of peaks, and standard deviation of peaks were selected as usable factors with a coefficient of determination ($r^2$) of 0.92 and a standard error of calibration (SEC) of 0.15. In the validation tests using twenty watermelon samples (sound 9, defective 11), the developed model provided good capability showing a classification accuracy of 95%.

• 한국안광학회지
• /
• 제5권1호
• /
• pp.139-146
• /
• 2000

눈의 굴정이상을 완전교정한 상태에서 양안시기능 알아보기 위해서 maddox rod를 이용하여 안구 편위량을 측정한 결과, 수평방향의 편위가 없는 정위는 10%, 내사위 55%, 외사위 34%로 나타났으며, 안구의 내측 편위가 외측편위보다 11% 많은 것으로 나타났다. 또한 4 프리즘 이상의 편위량을 갖고 있는 경우도 내사위 23%, 외사위 9%로 나타나 보다 쾌적한 양안시 기능을 유지하기 위해서는 안위이상을 고려한 처방이 되어야 한다. 굴절이상 교정별 안위 이상을 측정한 결과 저교정에서 과교정 상태로 감에 따라 안위의 편위는, 외사위는 감소하고, 내사위는 그 정도가 증가하는 경향을 보였는데 이는 조절의 영향일 것으로 생각된다. 또한, heterophona 법으로 AC/A 비를 측정한 결과, 최저 1.25에서 6.61까지 분포하고 있었으며 굴절이상과는 관련성을 찾아볼 수 없었다.

• 한국재료학회지
• /
• 제22권1호
• /
• pp.16-23
• /
• 2012

Research into the development of high strength (1 GPa) and superior formability, such as total elongation (10%), and stretch-flangeability (50%) in hot-rolled steel was conducted with a thermomechanically controlled hot-rolling process. To improve the overall mechanical properties simultaneously, low-carbon steel using precipitation hardening of Ti-Nb-V multimicroalloying elements was employed. And, ideal microstructural characteristics for the realization of balanced mechanical properties were determined using SEM, EBSD, and TEM analyses. The developed steel, 0.06C-2.0Mn-0.5Cr-0.2(Ti + Nb + V), consisted of ferrite as the matrix phase and second phase of granular bainite with fine carbides (20-50 nm) in both phases. The significant factor of the microstructural characteristics that affect stretch-flangeability was found to be the microstructural homogeneity. The microstructural homogeneity, manifest in such characteristics as low localization of plastic strain and internally stored energy, was identified by grain average misorientation method, analyzed by electron backscattered diffraction (EBSD) and hardness deviation between the phases. In summar, a hot-rolled steel having a composition 0.06C-2.0Mn-0.5Cr-0.2(Ti + Nb + V) demonstrated a tensile strength of 998 MPa, a total elongation of 19%, and a hole expansion ratio of 65%. The most important factors to satisfy the mechanical property were the presence of fine carbides and the microstructural homogeneity, which provided low hardness deviation between the phases.

• 대한간호학회지
• /
• 제41권6호
• /
• pp.788-794
• /
• 2011

Purpose: Reduced heart rate variability significantly increases cardiovascular mortality. Metabolic syndrome increases the cardiac autonomic dysfunction. Recently, increasing cardiovascular mortality has been reported in patients with schizophrenia. This study was done to compare heart rate variability between adults with and without schizophrenia and to compare the relationship of heart rate variability to metabolic syndrome in hospitalized patients with schizophrenia. Methods: This was a descriptive and correlational study in which 719 adults without schizophrenia and 308 adults with schizophrenia took part between May and June 2008. We measured the following: five-minute heart rate variability; high-frequency, low-frequency, the ratio of low-frequency to high-frequency, and the Standard Deviation of all the normal RR intervals. Data was also collected on metabolic syndrome, abdominal obesity, triglycerides, HDL cholesterol, blood pressure and fasting glucose. Results: The Standard Deviation of all the normal RR intervals values of heart rate variability indices were $1.53{\pm}0.18$. The low-frequency and high-frequency values of heart rate variability indices were significantly higher in hospitalized patients with schizophrenia ($3.89{\pm}1.36$; $3.80{\pm}1.20$) than those in the healthy participants ($2.20{\pm}0.46$; $2.10{\pm}0.46$). There were no significant differences between the schizophrenic patients with and without metabolic syndrome. Conclusion: The results of this study indicate that schizophrenia patients have significantly lower cardiac autonomic control, but they have significantly higher low-frequency and high-frequency values than those of healthy adults. Use of antipsychotic drug may affect the autonomic nervous system in schizophrenic patients. Metabolic syndrome was not associated with cardiac autonomic control in schizophrenia patients.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.69-74
• /
• 2006

Recently, spillways are need to control stable water level for supporting main dams because of floods by unusual change of weather such as Typhoon Rusa. This study has been focused on the amount of leakage through the rock mass distributed fractures and joints under the opened emergency spillway. It is very important to evaluate the amount of leakage as these affect stability of spillway by interaction between effective stress and pore pressure. The commercial program MAFIC has been used for analyzing groundwater flow in fractured rock mass. The results showed that the values of range, average and deviation of leakage were $2.85\sim\;3.79\times10^{-1}$, $3.32\times10^{-1}$ and $1.70\times10^{-2}\;m^3/day/m^2$ respectively. Secondary, we have estimated the effect of grouting after the transmissivity$(T_f)$ of joint 1 as main pathway of leakage known from above results was changed from $1.78\times10^{-7}$ to $1.59\times10^{-9}\;m^2/s$. The results showed that the values of range, average and deviation of leakage were $7.80\times10^{-4}\sim1.53\times10^{-3}$, $1.18\times10^{-3}$ and $1.32\times10^{-4}\;m^3/day/m^2$ respectively. As the result, the amount of leakage after grouting has been decreased by a ratio of 1 to 277.

• 한국통신학회논문지
• /
• 제24권8A호
• /
• pp.1107-1114
• /
• 1999

본 논문에서는 대수정규 쉐도잉(shadowing)과 나카가미(Nakagami) 페이딩을 함께 받은 타 시스템의 동일 채널 간섭파가 불완전 전력제어 된 DS/CDMA 셀룰러 시스템의 용량에 미치는 영향을 분석하였다. 분석에는 먼저 간섭을 고려하지 않고 불완전 전력제어만을 해석한 Prasad와 Jansen의 결과와 비교하였으며, 대수정규-나카가미 페이딩을 받은 다중 간섭은 Schwartz와 Yeh가 제시한 방법을 적용하여 DS/CDMA 시스템에 미치는 영향을 오수신확률로 유도하였다. 유도한 오수신확률에 대해 불완전 전력제어, 페이딩 지수, 처리이득, 전력비, 간섭수, 음성화율 등을 파라미터로 하여 각각의 상황에서 DS/CDMA 시스템의 가입자 용량 감소를 분석하였다. 결과로부터 DS/CDMA 시스템의 용량은 전력제어 오차와 간섭파의 증가에 매우 민감하여 전력제어 오차가 클수록, 무선채널 환경의 페이딩이 심할수록, 또한 간섭파의 수가 증가할수록 감소하였다.

• 센서학회지
• /
• 제25권2호
• /
• pp.124-130
• /
• 2016

NDIR $CO_2$ gas sensor was built with ASIC implemented thermopile sensor which included temperature sensor and unique elliptical waveguide structures in this paper. The temperature dependency of dual infrared sensor module ($CO_2$ and reference IR sensors) has been characterized and its output voltage characteristics according to the temperature and gas concentration were proposed for the first time. NDIR $CO_2$ gas and reference IR sensors showed linear output voltages according to the variation of ambient temperatures from 243 K to 333 K and their slopes were 14.2 mV/K and 8.8 mV/K, respectively. The output voltages of temperature sensor also presented a linear dependency according to the ambient temperature and could be described with V(T)=-3.191+0.0148T(V). The output voltage ratio between $CO_2$ and reference IR sensors revealed irrelevant to the changes of ambient temperatures and gave a constant value around 1.6255 with standard deviation 0.008 at 0 ppm. The output voltage of $CO_2$ gas sensor at zero ppm $CO_2$ gas consisted of two components; one is caused by the HPB (half pass-band) of IR filter and the other is attributed to the part of $CO_2$ absorption wavelength. The characteristics of output voltages of $CO_2$ gas sensor could be accurately modeled with three parameters which are dependent upon the ambient temperatures and represented small average error less than 1.5% with 5% standard deviation.

• Asian-Australasian Journal of Animal Sciences
• /
• 제26권6호
• /
• pp.864-873
• /
• 2013

In developing countries, biogas energy production is seen as a technology that can provide clean energy in poor regions and reduce pollution caused by animal manure. Laboratories in these countries have little access to advanced gas measuring equipment, which may limit research aimed at improving local adapted biogas production. They may also be unable to produce valid estimates of an international standard that can be used for articles published in international peer-reviewed science journals. This study tested and validated methods for measuring total biogas and methane ($CH_4$) production using batch fermentation and for characterizing the biomass. The biochemical methane potential (BMP) ($CH_4$ NL $kg^{-1}$ VS) of pig manure, cow manure and cellulose determined with the Moller and VDI methods was not significantly different in this test (p>0.05). The biodegradability using a ratio of BMP and theoretical BMP (TBMP) was slightly higher using the Hansen method, but differences were not significant. Degradation rate assessed by methane formation rate showed wide variation within the batch method tested. The first-order kinetics constant k for the cumulative methane production curve was highest when two animal manures were fermented using the VDI 4630 method, indicating that this method was able to reach steady conditions in a shorter time, reducing fermentation duration. In precision tests, the repeatability of the relative standard deviation (RSDr) for all batch methods was very low (4.8 to 8.1%), while the reproducibility of the relative standard deviation (RSDR) varied widely, from 7.3 to 19.8%. In determination of biomethane concentration, the values obtained using the liquid replacement method (LRM) were comparable to those obtained using gas chromatography (GC). This indicates that the LRM method could be used to determine biomethane concentration in biogas in laboratories with limited access to GC.